A comparison of reproductive and growth traits of horned and polled cattle in three synthetic beef lines

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1 A comparison of reproductive and growth traits of horned and polled cattle in three synthetic beef lines L.A. Goonewardene 1, H. Pang 1, R.T. Berg 2, and M.A. Price 2 1 Animal Industry Division, Alberta Agriculture Food and Rural Development, # Street, Edmonton, Alberta, Canada T6H 5T6; 2 Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5. Received 23 September 1998, accepted 27 January Goonewardene, L. A., Pang, H., Berg, R. T. and Price, M. A A comparison of reproductive and growth traits of horned and polled cattle in three synthetic beef lines. Can. J. Anim. Sci. 79: The data for the study were obtained over an 11- yr period and the number of observations varied from 2663 to 4263 depending on the trait that was studied. The objective was to compare the reproduction and growth traits of genetically horned and polled cattle in three synthetic lines of beef cattle. No differences (P > 0.05) were observed between horned and polled cattle in all lines for pregnancy, calving and weaning rates, calf birth and weaning weights, calf preweaning average daily gains, dystocia score, cow weights and cow condition scores at calf birth and calf weaning. We advocate the use of polled cattle for breeding, which is a welfare friendly alternative and circumvents the need for dehorning. Key words: Horned, polled cattle, dehorning, reproduction, growth Goonewardene, L. A., Pang, H., Berg, R. T. et Price, M. A Comparaisons des caractères de croissance et de reproduction des sujets à corne et sans corne dans trois souches synthétiques de bovins à viande. Can. J. Anim. Sci. 79: Nous avons comparé les caractères de croissance et de reproduction de bovins à cornes et de sujets sans cornes chez trois souches synthétiques de bovins à viande. Les données utilisées à cet effet portaient sur une période de 11 ans et comprenaient de à observations selon le caractère étudié. Aucune différence significative (P > 0,05) n était relevée dans les 3 souches entre les deux types d animaux quant aux taux de gravidité, de vêlage et de sevrage, au poids du veau à la naissance et au sevrage, au GMQ en prévêlage du veau, au taux de dystocie, au poids de la mère et à son état corporel à la naissance et au sevrage du veau. À la lumière de ces résultats, nous préconisons l utilisation pour la reproduction de sujets sans cornes, à la fois pour des raisons de bien-être des animaux et pour éliminer la nécessité de l écornage. Mots clés: Bovins à cornes, bovins sans cornes, écornage, reproduction, croissance Horned cattle often pose management problems and economic losses. Bruising the hides of other animals due to fighting or during transport, difficulties in moving them through narrow corridors or chutes and getting their horns caught in the head gate are a few of the more common problems. The economic costs to the Canadian beef industry due to horns was estimated at $ and due to bruising $ (Van Donkersgoed 1997). As such, the beef feedlot slaughter cattle industry appears to be most affected by the presence of horns. It is therefore recommended that horned cattle be dehorned during early stages in life (Grandin 1980). Although many commercial cattle are dehorned early in life, some are sold to feedlots with their horns on. The practice of removing horns at feedlot entry has been shown to reduce the weight gains by 23% in the first 2 wk and by 4.3% over a 106-d period (Goonewardene and Hand 1991). Dehorning cattle at 6 mo is deemed to be stressful (Cooper et al. 1995) and in the United Kingdom, dehorning cattle that are older than 1 wk of age requires that it be done by a veterinarian using an anesthetic (UK Ministry of Agriculture, Fisheries and Food 1992). Despite some evidence in the literature suggesting that there is little or no difference between horned and polled genotypes of some cattle breeds (Frisch et al. 1980; Lange 1989; Stookey and Goonewardene 1996), horned and polled 123 cattle breeders tend to breed within horn status groups. Blockey and Taylor (1984) reported reduced fertility among polled Hereford bulls due to a genetic, premature spiral deviation of the penis, which may discourage the use of polled Hereford bulls in some circumstances. However, using polled cattle free of genetic defects and reducing the frequency of the horned gene over time (as the expression of polledness is dominant to horned) is one method of circumventing the need for dehorning. Final recommendations on whether to use polled bulls would have to be based on phenotypic similarities between polled and horned for traits associated with growth, reproduction of males and females, and carcass quality attributes. The objective of the study was to compare the reproduction and growth traits of genetically horned and polled cattle in three synthetic lines of beef cattle. Abbreviations: ADG, average daily gain; BS, Beef Synthetic; BS1, Beef Synthetic 1; BS2, Beef Synthetic 2; CS, condition score; DBS, Dairy-Beef Synthetic; H, horned; P, polled

2 124 CANADIAN JOURNAL OF ANIMAL SCIENCE MATERIALS AND METHODS All animals used for the study were managed according to the guidelines of the Canadian Council on Animal Care (1984). The data were obtained from three synthetic lines of beef cattle at the University of Alberta beef ranch in Kinsella, over an 11-yr period from 1985 to The pregnancy, calving and weaning rate data relating to the cows were obtained between 1987 and The three lines studied were: Dairy-Beef Synthetic (DBS), Beef Synthetic 1 (BS1) and Beef Synthetic 2 (BS2). The breed composition of the synthetic lines and management practices were described in an earlier report (Berg et al. 1990). Briefly, the DBS is composed of approximately 60% dairy breeds (Holstein, Brown Swiss or Simmental) and 40% beef breeds. The BS1 is composed of 33% each of Angus and Charolais, 20% Galloway, with the remainder comprising of other beef breeds, while the BS2 is made up of approximately 60% Hereford and 40% other beef breeds. The ranch, which is located in east central Alberta, is managed as a commercial unit. The annual precipitation is around 48 cm. Winters in this part of Alberta persist to the end of March, and April snowstorms often occur. All synthetic lines were maintained and managed similarly, and were subject to the same selection program. Medium birth weight bulls that showed high pre- and post-weaning gain were selected for breeding. Selection of male and female breeding stock was independent of their horn status. Cows and heifers were bred in multiple sire breeding groups within each line on pasture and the breeding period was approximately 60 d. Bred females were pregnancy checked 4 mo after breeding. Heifers and cows failing to wean a calf in any year were culled. The breeding herds grazed a mixture of native rough fescue and improved pastures year round and were supplemented with an alfalfa brome hay and green feed (oats) during the winter. Cows were wintered on open range pastures, which were either minimally grazed or not grazed in the previous summer. The pastures contained poplar bluff shelters. Winter supplementation usually began in December and continued through to March. Straw bedding was provided for cows and heifers on the range. Cows calved in the open range and heifers calved out in a separate pasture, which was easily accessible. Within the first week after birth horn buds were removed from horned calves by applying a caustic paste. Calves were weaned on the same date each year either in September or October, and following a 28-d adjustment period, all males were placed on a standard Canadian feed test. After an adjustment period of 3 wk following weaning, heifer calves were fed 2.27 kg roughage (grass and alfalfa hay) and 2.27 kg grain (66% barley 33% oats) and a mineral supplement daily until the following April, when they were transferred to pasture. These heifer calves also consumed some of the straw supplied as bedding and gained about 0.3 kg d 1 in drylot. The number of observations varied for the traits measured. The parameters measured, calculated or scored were pregnancy rate (n = 3225, H = 1479, P = 1746), calving rate (n = 3228, H = 1482, P = 1746), weaning rate (n = 3225, H = 1479, P = 1746), dystocia score (n = 4160, H = 2139, P = 2121), calf birth weight (n = 4263, H = 2140, P = 2123), Table 1. Reproductive traits by horn status, line and age of dam Rate (%) z Effect Levels Pregnancy Calving Weaning n y Horn status Horned Polled P NS x NS NS Line w DBS BS BS P NS NS NS Age of dam heifer (2 yr) 88.3a 83.5a 75.7a 3 5 yr 92.6b 90.4b 84.8b > 5 yr 91.1b 88.8b 87.2b P < 0.01 < 0.01 < 0.01 z Percent based on the number bred. x P > w DBS-Dairy-Beef Synthetic, BS1- Beef Synthetic 1, BS2-Beef Synthetic 2. a,b Denote rate (%) differences in age of dam tested by linear contrasts. weaning weight and age (n = 3540, H = 1809, P = 1731), calf preweaning ADG (n = 3460, H = 1764, P = 1696), cow weight at calf birth (n = 2663, H = 1309, P = 1355), cow weight at calf weaning (n = 2946, H = 1493, P = 1453), cow CS at birth (n = 4346, H = 2188, P = 2158) and cow CS at calf weaning (n = 3071, H = 1547, P = 1524). Pregnancy, calving and weaning rates, were based on the number of females bred, expressed as a percentage. Dystocia was scored on a scale of 0 to 5, where 0 = no difficulty, 1 = light pull, 2 = hard pull, 3 = forceps used, 4 = veterinary assistance and 5 = Caesarian section (Naazie et al ). The five-point condition scoring system developed by the east of Scotland College of Agriculture was followed (Lowman et al. 1986). Pregnancy, calving and weaning rates were analyzed by the CATMOD procedure in SAS (SAS Institute, Inc. 1985) with linear contrasts to separate effects of horn status, line and age of dam. The age of dam was described in three groupings, heifers (2 yr), 3 5 yr-old and cows greater than 5 yr of age. Calf birth weight, weaning weight and preweaning ADG, cow weight and condition scores at calf birth and weaning, dystocia score and calf weaning age were analyzed by the General Linear Model in SAS. Dystocia scores were converted to five scores (Snell 1962) where, no difficulty was scored 0, light pull (1) was scored 42, hard pull (2) was scored 65, forceps used (3) was scored 76 and veterinary assistance and Caesarian section (4 and 5) scored 100, and these transformed scores were analyzed as a continuous variable. This transformation provides homogenous residual variances over the subclasses and approximately normally distributed residual deviations (Tong et al. 1977; Naazi et al. 1989). The fixed effects for the calf traits in the model included horn status (genetically horned or polled), line (DBS, BS1, BS2), year ( ), age of dam (2, 3, 4, 5, 6 yr), sex (male and female) and interactions between horn status and the other fixed effects. Calf weaning weight and preweaning ADG were adjusted using weaning age as a covariate. The fixed effects for the cow traits in the model included all other than sex.

3 GOONEWARDENE ET AL. A COMPARISON OF HORNED AND POLLED CATTLE 125 Table 2. Least squares means for calf birth weight and weaning traits by horn status, line, age of dam and sex of calf Birth weight Wean weight Wean age Prewean ADG z Effect Levels (kg) (kg) (d) (kg d 1 ) n y Horn status Horned 38.5 ± ± ± ± Polled 38.5 ± ± ± ± P Line x DBS 40.1 ± 0.20a ± 0.90a 160 ± ± 0.005a BS ± 0.16b ± 0.73b 159 ± ± 0.004b BS ± 0.15c ± 0.70c 160 ± ± 0.004c P < 0.01 < < 0.01 Age of dam 2 yr w 33.8 ± 0.17a ± 0.78a 162 ± 0.5c 0.99 ± 0.004a 3 yr 37.6 ± 0.20b ± 0.95b 160 ± 0.6b 1.10 ± 0.005b 4 yr 39.5 ± 0.24c ± 1.13c 161 ± 0.7bc 1.13 ± 0.006c 5 yr 41.1 ± 0.28d ± 1.25d 158 ± 0.8a 1.17 ± 0.007d 6 yr 40.6 ± 0.17d ± 0.78d 159 ± 0.5ab 1.17 ± 0.007d P < 0.01 < 0.01 < 0.01 < 0.01 Sex Female 37.0 ± 0.14 a ± ± ± Male 40.0 ± 0.13 b ± ± ± P < 0.01 < < 0.01 z Average daily gain. x DBS-Dairy-Beef Synthetic, BS1- Beef Synthetic 1, BS2-Beef Synthetic 2. w Heifer. a d Means with different letters denote significance P < RESULTS Pregnancy, calving and weaning rates expressed as a percentage by horn status, line and age of the dam is shown in Table 1. No differences (P > 0.05) were observed for pregnancy, calving or weaning rate between genetically horned (phenotypically dehorned) and polled or between the DBS, BS1 and BS2 lines. However, heifers had lower (P < 0.01) pregnancy, calving and weaning rates compared with the older cows. The least square means for calf birth weight and preweaning traits are shown in Table 2. No differences (P > 0.01) were observed between horned and polled cattle for any of the calf traits. Differences between breed lines were significant (P < 0.01) for birth weight, weaning weight and preweaning ADG, with DBS showing highest values and BS2 showing the lowest values. Calves from heifers were lighter at birth, weaning and had lower (P < 0.01) preweaning ADG compared with calves from older cows. Male calves were heavier (P < 0.01) than female calves at birth and weaning and showed higher (P < 0.01) preweaning ADG. Cow traits such as dystocia score, cow weight and condition score when the calves were born and weaned (Table 3) were not different for horned and polled cattle (P > 0.05). None of the interactions between horn status and the fixed effects such as line, age of dam, sex of calf and year was significant (P > 0.05) for the traits studied. DISCUSSION The similarities in reproduction and growth traits between genetically horned and polled cattle in this study agree with those of Frisch et al. (1980) and Lange et al. (1990). Pregnancy, calving and weaning rates, birth weight, preweaning ADG, cow weights and condition scores agree with the results of Pang et al. (1998) for the three lines of cattle on the same farm. Although the polled condition is dominant in expression to horned (Long and Gregory 1978) and certain beef breeds such as the Angus and Charolais were originally developed to be polled, many crossbred commercial cattle are horned. It is likely that the horned genes were reintroduced into commercial herds by outcrossing with other horned breeds and crossbreds. In a recent Alberta survey, 14.8% of the commercial slaughter cattle were found to have full horns, while 25.2% had scurs, tips or horn stubs (Van Donkersgoed et al. 1997). In our study, the ratio of genetically horned to polled animals was approximately 1:1. It is therefore evident that a significant proportion of slaughter cattle need to be dehorned early in life so as to reduce the injury to live animals, damage to edible tissues and bruising of hides, all of which result in economic losses (Grandin 1980; Van Donkersgoed et al. 1997). Earlier studies have shown that dehorning older cattle is both stressful and results in reduced growth rates (Wilks et al. 1977; Grandin 1980; Goonewardene and Hand 1991; Cooper et al. 1995). Yet some cattle are dehorned late in life and others are slaughtered with their horns on. Although data from the present study, and evidence from other studies in the literature suggest that phenotypic differences in traits associated with reproduction, growth and the carcass, between horned and polled cattle are small and of little significance (Frisch et al. 1980; Lange et al. 1990; Stookey and Goonewardene 1996), there has been a tendency on the part of pure-bred breeders to keep horned and polled populations separate (Koots and Crow 1989). The only strong negative attribute to using polled bulls arises from an implied effect of reduced fertility due to the frequent occurrence of a spirally deviated penis among polled Herefords (Blockey and Taylor 1984). However, as evidenced by the bull test station data from Saskatchewan (Stookey and Goonewardene 1996), there is a

4 126 CANADIAN JOURNAL OF ANIMAL SCIENCE Table 3. Least squares means for dystocia and cow traits by horn status, line, age of dam and sex of calf Cow wt birth Cow wt wean Effect Levels Dystocia (kg) (kg) Cow CS z birth Cow CS wean n y Horn status Horned 4.5 ± ± ± ± ± 0.01 Polled 5.0 ± ± ± ± ± 0.01 P Line x DBS 4.3 ± ± 2.7a ± 2.3a 2.6 ± 0.01a 3.0 ± 0.01a BS1 4.5 ± ± 2.3b ± 1.8b 2.7 ± 0.01b 3.3 ± 0.01b BS2 4.5 ± ± 1.8c ± 1.8c 2.8 ± 0.01c 3.4 ± 0.01c P 0.16 < 0.01 < 0.01 < 0.01 < 0.01 Age of dam 2 yr w 17.7 ± 0.46a ± 2.0a ± 2.2a 2.6 ± 0.01a 3.0 ± 0.01a 3 yr 2.6 ± 0.58b ± 2.7b ± 2.3b 2.6 ± 0.01a 3.1 ± 0.01b 4 yr 1.6 ± 0.71b ± 3.0c ± 2.7c 2.7 ± 0.02b 3.2 ± 0.01c 5 yr 1.2 ± 0.81b ± 3.6d ± 3.1d 2.8 ± 0.02c 3.4 ± 0.01d 6 yr 0.6 ± 0.50b ± 2.4e ± 2.0e 2.9 ± 0.01d 3.5 ± 0.01e P < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 Sex Female 3.2 ± 0.40a Male 6.2 ± 0.38b P < 0.01 z Condition score. x DBS-Dairy-Beef Synthetic, BS1-Beef Synthetic 1, BS2-Beef Synthetic 2. w Heifer a e Means with different letters denote significance P < trend towards the greater use of polled Hereford and Charolais bulls. Our study shows clearly that phenotypic differences between polled and genetically horned synthetic crossbreds for traits associated with female reproduction and growth are small and of little significance. The differences between polled and horned cattle observed and reported by producers are often confounded by the intensities of selection placed on different traits, which vary among farms and by the differences due to management. As such, the observed differences may be unrelated to the presence or absence of horns. The code of practice for beef cattle suggests that castration and dehorning be performed at an early age, preferably before weaning, when the recovery time is relatively short. When it is necessary to castrate or dehorn a mature animal it is suggested that the operation be conducted in consultation with a veterinarian (Recommended Code of Practice for the Care and Handling of Beef Cattle 1991). The beef code of practice does not, however, suggest or address any methods of dehorning. The use of polled cattle to produce hornless types is a non-invasive alternative to all existing methods of dehorning. There is more evidence suggesting non-significant differences in production between horned and polled cattle, hence producers and scientists may want to recognize breeding for polledness as an alternate sustainable method of dehorning in the beef code of practice. We advocate the use of polled animals for breeding commercial slaughter cattle as it is a more welfare friendly alternative that negates the need for dehorning. Berg, R. T., Makarechian, M. and Arthur, P. F The University of Alberta beef breeding project after 30 years A review. University of Alberta, Annual Feeders Day Rep. 69: Blockey, M. A. and Taylor, E. G Observations on spiral deviation of the penis in beef bulls. Aust. Vet. J. 61: Canadian Council on Animal Care Guide to the care and use of experimental animals. Vol 2. CCAC, Ottawa, ON. Cooper, C., Evans, A. C. O., Cook, S. and Rawlings, N. C Cortisol, progesterone and beta-endorphin response to stress in calves. Can. J. Anim. Sci. 75: Frisch, J. E., Nishimura, H., Cousines, K. J. and Turner, G. H The inheritance and effect of polledness in four crossbred lines of beef cattle. Anim. Prod. 31: Goonewardene, L. A. and Hand, R. K Studies on dehorning steers in Alberta feedlots. Can. J. Anim. Sci. 71: Grandin, T Bruises and carcass damage. Int. J. Stud. Anim. Prob. 1: Koots, K. R. and Crow, G. H Breed structure of pedigreed Hereford cattle in Canada. Can. J. Anim. Sci. 69: Lang, H Investigations on polledness and head conformation in German Simmental cattle. Thesis, Ludwig Maximilians Universat Muchen, Federal Republic of Germany. Lange, H., Brem, G., Utz, J., Gottschalk, A., Karnbaum, B. and Krausslich, H Investigations on the polled condition in German Simmental cattle. Bayerisches Landwirtschaftliches Jahrbuch 67: Long, C. R. and Gregory, K. E Inheritance of the horned, scurred and polled condition in cattle. J. Herid. 69: Lowman, B. G., Scott, N. A. and Sommerville, S. H Condition scoring for cattle. East of Scotland College of Agriculture, November Edinburgh School of Agric. Edinbrugh, UK. Bull no. 6, 31 pp. Naazi, A., Makarechian, M. M. and Berg, R. T Factors influencing calving difficulty in beef heifers. J. Anim. Sci. 67: Naazie, A., Makarechian, M. M. and Berg, R. T Genetic aspects of calving difficulty in beef heifers. 69th Annual Feeders Day Report, University of Alberta, Edmonton, AB. pp Pang, H., Makarechian, M., Goonewardene, L. A. and Berg, R. T Effects of early versus late spring calving on beef cow

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